This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-275494, filed Sep. 20, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a liquid-cooled electronic apparatus that has radiators provided at the back of a display panel and is designed to radiate heat from, for example a CPU (Central Processing Unit). More particularly, the invention relates to the structure of the radiators in which liquid coolant flows.
2. Description of the Related Art
A CPU is incorporated in, for example, notebook-type portable computers. The heat that the CPU generates while operating increases as its data-processing speed rises and it performs more and more functions. The higher the temperature of the CPU, the less efficiently it operates. To cool the CPU, so-called cooling system of liquid cooling type has been developed in recent years. A liquid-cooling system uses a liquid coolant that has a far higher specific heat than air.
Japanese Patent Application KOKAI publication No. 7-142886 discloses a cooling system of liquid cooling type, configured for use in portable computers that comprise a main unit and a display unit. The cooling system comprises a heat-receiving header, heat-radiating header, and a tube. The heat-receiving header is provided in the main unit and is thermally connected to the CPU incorporated in the main unit. The heat-radiating header is provided in the display unit and is located at the back of the display panel incorporated in the display unit. The tube extends from the main unit to the display unit to circulate the liquid coolant between the heat-receiving header and the heat-radiating header.
The display unit has a display housing. The display housing contains the display panel and the heat-radiating header. The heat-radiating header is provided between the back of the display housing and the display panel. The heat-radiating header is thermally connected to the back of the display housing. The liquid coolant transfers the heat of the CPU from the heat-radiating header to the display housing. The heat is radiated from the surface of the display housing.
The higher the surface temperature of the display housing, the greater the amount of heat radiated from the display housing. In other words, the heat-radiating efficiency of the heat-radiating header is proportional to the surface temperature of the display housing. However, the surface temperature of the display housing cannot be raised so much. This is because the user needs to touch the display housing to open or close the display unit.
Some measures should be taken to prevent the surface temperature of the display housing from increasing over, for example, 60xc2x0 C. If such measures are taken, however, the amount of heat that may be radiated from the heat-radiating header will be 10-odd watts (W) at best. Consequently, the conventional cooling system cannot cool the CPU as much as desired. The system may fail to radiate the increasing amount of heat that the CPU generates while operating.
According to an embodiment of the present invention, there is provided an electronic apparatus comprising: a heat-generating component; a main unit having a heat-receiving portion thermally connected to the heat-generating component; a display unit supported by the main unit; a heat-radiating portion provided in the display unit and radiating the heat generated by the heat-generating component; and a circulating path circulating liquid coolant between the heat-receiving portion and the heat-radiating portion. The heat-radiating portion includes a first radiator and a second radiator. The radiators are connected in series in a direction in which the liquid coolant flows. The second radiator is located at the downstream of the liquid coolant, and is exposed outside the display unit.